1. Field of the Invention
The present invention relates to a cuff for a blood pressure monitor and, more particularly, to a cuff characterized by a curled elastic member disposed on the outside of a bladder to hold a ring form of the cuff.
2. Description of the Related Art
As shown in FIG. 11 (perspective view) and FIG. 12 (sectional view), a cuff for a blood pressure monitor has generally a configuration such that a bladder 91 and a curled elastic member 92 are provided in a cloth bag 90. A tube 93 is connected to the bladder 91, and a velcro fastener 94 is attached on the outside of the cloth bag 90. The curled elastic member 92 is disposed on the outside of the bladder 91 to hold the cuff in a ring form by its elasticity. As shown in FIG. 13A, the curled elastic member 92 has an uniform thickness and has a sectional shape of a complete round in which a part thereof is a discontinuous portion 92a. 
However, the curled elastic member 92 as shown in FIG. 13A has the following problems 1 to 3.
1. Operation of uncurling the curled elastic member 92 to be attached on an arm is not easy.
Since the sectional shape is a complete round, the curled elastic member 92 has to be uncurled and then attached on an arm. Specifically, in order to uncurl the curled elastic member 92, it has to be pulled with some strength. The user needs some experience to attach the elastic member 92 in the uncurled state onto his/her arm.
2. The end portions of the curled elastic member 92 cut into the flesh of the arm.
In the case of the curled elastic body 92 having the sectional shape of complete round, when it is attached around the arm, the edges of the discontinuous portion 92a cut into the flesh of the arm and the subject often feels pain. Particularly, in the case of a big arm, such a tendency is conspicuous.
3. The shape of the curled elastic member 92 cannot be altered according to the size and shape of an arm such as slender arm, big arm, tapered arm (arm of which size changes largely from the shoulder to the elbow), straight arm (arm of which size changes little from the shoulder to the elbow) or the like, so that the curled elastic member 92 is not easily fit to an arm.
This is because the thickness of the curled elastic member 92 is uniform and the sectional shape thereof is a complete round. Although the size and shape of an arm vary widely with the individual, the curled elastic member 92 does not have a form which can be easily fit to every one.
On the other hand, a curled elastic member having increased fitness which can be attached to an arm more easily has been proposed as shown in FIG. 13B (Japanese Unexamined Patent Publication No. 61-238229 (1987)). This curled elastic member 92xe2x80x2 is formed so that its thickness gradually increases from the both ends (discontinuous portion 92xe2x80x2a) toward the center portion and, accordingly, the rigidity gradually increases. The thickness and rigidity are the maximum in the center portion.
However, even in the curled elastic member 92xe2x80x2, since the thickness is simply gradually increased from the both ends toward the center portion, the shape is not flexibly altered to be adapted to various arms, and it has room for improvement. A provision of a curled elastic member having more excellent performance is awaited.
The present invention has been achieved by paying attention to such conventional problems and circumstances and an object of the present invention is to provide a cuff for a blood pressure monitor having a curled elastic member which can be easily attached to an arm, does not make the subject feel pain when attached, and exhibits the characteristic of excellent fitness.
In order to achieve the above-mentioned object, a cuff for a blood pressure monitor of the present invention having therein a bladder and a curled elastic member disposed on the outside of the bladder to hold a ring shape of the cuff, wherein one end portion of the curled elastic member is extended outward so as to enwind the other end portion inward.
In the curled elastic member, at the time of attachment to an arm, the one end portion extended outward is thrown over the arm, and the curled elastic member can be put on the arm while being largely uncurled. That is, the operation of uncurling the curled elastic member and the operation of attaching the curled elastic member to an arm can be simultaneously performed, so that the operation of attachment to an arm is easy. Since the curled elastic member has such a form that the one end portion is longer than the other end portion and the other end portion is enwinded inward, the end portions do not easily cut in the flesh of an arm when attached, so that the subject does not feel pain.
According to another embodiment of the curled elastic member, a sectional shape of the curled elastic member is approximately triangle and one end portion of the curled elastic member is extended. By the curled elastic member as well, equivalent action and effects can be obtained.
According to further another embodiment, the curled elastic member has a narrow portion in which width in the axial direction of an arm is partly narrowed or a thin portion in which thickness is partly reduced between an approximately center portion in the circumferential direction of the arm and both end portions. In this case, the elasticity and alteration in the shape can be adjusted by the narrow portion or the thin portion. That is, by the narrow portion or the thin portion, the curled elastic member (i.e., the cuff) gets easily to be twisted. Thus, the curled elastic member is fit more easily to an arm of any shape such as a straight arm or tapered arm.
Moreover, the narrow portion or thin portion is not provided as the both end portions of the curled elastic member, so that the rigidity of the both end portions is not reduced and an arm can be securely held by the both end portions. Furthermore, by not particularly providing the narrow portion as the both end portions of the curled elastic member, as compared with the case where the both end portions are narrowed, the subject does not have strange feeling such that the both end portions cut into the flesh of the arm.
In the case of the form in which the curled elastic member has the narrow portion, although the form may be used satisfactorily, it is preferable to construct a portion missed by narrowing the width to form the narrow portion by a thin portion which is thinner than the narrow portion. This is because that if the portion missed by the narrow portion exists, when the bladder is inflated, it is feared that the bladder is inflated from the side (missing portion) of the narrow portion to the surface side of the cuff so that the arm cannot be sufficiently pressed, and there is also the possibility such that, in a process of taking blood pressure data while changing air pressure, noise occurs due to inflation from the missing portion to the outside of the bladder so that blood pressure cannot be measured stably.
The configuration in which the missing portion generated due to the narrow portion is formed as the thin portion aims at obtaining an effect such that, while maintaining fitness by the both end portions, the curled elastic member is easily twisted so as to be fit to any of arms of various shapes such as straight arm or tapered arm.
The narrow portion may have a constant width in the circumferential direction of an arm or a width gradually reduced from the center portion toward both end portions.
According to further another embodiment, an inner circumferential face of the curled elastic member may have an approximately round shape and an outer circumferential face of the curled elastic member may have an approximately polygon shape. In other words, the curled elastic member has a sectional shape such that the round inner circumferential face is inscribed in the polygonal outer circumferential face (strictly, it is not inscribed). The curled elastic member is thick at corner portions of the polygon and is thin in the side portions. Therefore, the form in which the thickness of the curled elastic member is substantially changed is obtained. In a manner similar to the curled elastic member having the portion of which shape is altered, the shape can be altered in correspondence with variations in arms. The curled elastic member does not easily cut in the flesh of an arm and has an excellent fitness to an arm.
A curled elastic member having the structure quite different from that of the above-mentioned curled elastic member may be also used. The curled elastic member is formed by connecting a plurality of elastic pieces by hinges, and energizing means for energizing the elastic member in a direction of uncurling the elastic member when the elastic member is uncurled at a predetermined angle or more, and energizing the elastic member in a direction of curling the elastic member when the elastic member is curled at a predetermined angle or less is provided on the hinged portions of the respective elastic pieces.
In the curled elastic member, the energizing force to the uncurling direction and the energizing force to the curling direction are given by the energizing means rather than the elasticity of the elastic pieces. The energizing force changes by using uncurling of the elastic member at a predetermined angle as a branch point. That is, when the elastic member is largely uncurled at the time of attachment to an arm, it is automatically largely uncurled by the energizing means. When the elastic member is curled at the time of fixing to the arm, it is automatically curled by the energizing means and fits to the arm.